Many semiconductor processing operations require the distribution of process gases across a large area, e.g., across a semiconductor wafer. Such distribution of gas is often accomplished through the use of a showerhead, which is typically a device that has a large number of small gas ports or gas distribution holes distributed across a generally circular area of approximately the same size as the semiconductor wafer. The process gases are fed into an internal plenum of the showerhead that is in fluidic communication with the gas ports. The process gases introduced into the internal plenum are thus able to flow through the gas ports and out onto the wafer (which is centered below the showerhead).
In some processes, multiple different gases are flowed through the showerhead in a sequential fashion to perform different steps of a semiconductor process. In other processes, like atomic layer deposition, the showerhead may have two or more internal plenums that are fluidically isolated from one another within the showerhead. Each of these internal plenums may be used to deliver a different gas to the wafer via gas ports that are dedicated to each internal plenum. Such separate plenum arrangements prevent the reactants used from mixing, which can cause a chemical reaction, before they leave the showerhead. This reduces clogging and other types of damage within the showerhead.
The plenums in showerheads are typically provided gas by way of one or more inlet tubes that are often connected directly to the showerhead. Discussed herein are improved showerhead inlet designs that provide enhanced performance over traditional inlets.